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• fastest (low latency) method for Inter Process Communication between Java and C/C++

  - by Bastien

  Hello, I have a Java app, connecting through TCP socket to a "server" developed in C/C++. both app & server are running on the same machine, a Solaris box (but we're considering migrating to Linux eventually). type of data exchanged is simple messages (login, login ACK, then client asks for something, server replies). each message is around 300 bytes long. Currently we're using Sockets, and all is OK, however I'm looking for a faster way to exchange data (lower latency), using IPC methods. I've been researching the net and came up with references to the following technologies: - shared memory - pipes - queues but I couldn't find proper analysis of their respective performances, neither how to implement them in both JAVA and C/C++ (so that they can talk to each other), except maybe pipes that I could imagine how to do. can anyone comment about performances & feasibility of each method in this context ? any pointer / link to useful implementation information ? thanks for your help

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• http(/* argument here */) How is this Object (Http) being used without an explicit or implicit meth

  - by Randin

  In the example for coding with Json using Databinder Dispatch Nathan uses an Object (Http) without a method, shown here: import dispatch._ import Http._ Http("http://www.fox.com/dollhouse/" >>> System.out ) How is he doing this? Thank you for all of the answers unfortunatly I was not specific enough... It looks like it is simply passing an argument to a constructor of class or companion object Http. In another example, I've seen another form: http = new Http http(/* argument here */) Is this valid Scala? I guess it must be, because the author is a Scala expert. But it makes no sense to me. Actions are usually performed by invoking methods on objects, whether explicitly as object.doSomething() or implicitly as object = something (using the apply() method underneath the syntactic sugar). All I can think of is that a constructor is being used to do something in addition to constructing an object. In other words, it is having side effects, such as in this case going off and doing something on the web.

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• can I override/redefine "global" Javascript functions, like confirm() and alert()?

  - by EndangeringSpecies

  I want to do some browser automation, and those pesky confirm/alert boxes are a real pain. Disabling javascript completely in this case is not an option, unfortunately. Well, so I was wondering, can I just change the definition of those methods as seen by my browser's javascript interpreter to basically do nothing and return true? Note that I do know about redefining them in the Javascript code directly, e.g. putting in function alert(message) { return true; } but AFAIK this is not a viable approach for this situation because when doing browser automation I have to work with other people's Javascript. Moreover, my program actually begins manipulating these websites already after the page has fully loaded into the browser, so I cannot just first automatically rewrite the javascript and then load the page. Well, so I was wondering if I could instead just "permanently" modify the way alert/confirm are implemented and executed in my browser. Sort of like the equivalent of dll injection and so forth in the realm of windows apps.

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• Inheriting from class that inherits from DynamicObject

  - by SeveQ

  Hello there, I'm experimenting with C# 4.0's dynamic object model. I've created an abstract class named "Block" that inherits from DynamicObject. It overrides TryGetMember and TrySetMember. Furthermore I've created a usable class named "Brush" that inherits from "Block". I want it to be usable dynamically. But when I create a dynamic object from it and try to access a runtime bound member, it pelts me with an exception telling me that the member doesn't exist. The overridden TryGetMember or TrySetMember methods of the abstract parent class aren't getting called. Is this behaviour to be expected? Thank you!

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• Annotate and Aggregate function in django

  - by thesteve

  In django I have the following tables and am trying to count the number of votes by item. class Votes(models.Model): user = models.ForeignKey(User) item = models.ForeignKey(Item) class Item(models.Model): name = models.CharField() description = models.TextField() I have the following queryset queryset = Votes.objects.values('item__name').annotate(Count('item')) that returns a list with item name and view count but not the item object. How can I set it up so that the object is returned instead of just the string value? I have been messing around with Manager and Queryset methods, that the right track? Any advice would be appreciated.

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• How do I Call a method from other Class

  - by balexandre

  Hi guys, I'm having some trouble figuring out to call methods that I have in other classes #import "myNewClass.h" #import "MainViewController.h" @implementation MainViewController @synthesize txtUsername; @synthesize txtPassword; @synthesize lblUserMessage; - (IBAction)calculateSecret { NSString *usec = [self calculateSecretForUser:txtUsername.text withPassword:txtPassword.text]; [lblUserMessage setText:usec]; [usec release]; } ... myNewClass.h #import <Foundation/Foundation.h> @interface myNewClass : NSObject { } - (NSString*)CalculateSecretForUser:(NSString *)user withPassword:(NSString *)pwd; @end myNewClass.m #import "myNewClass.h" @implementation myNewClass - (NSString*)CalculateSecretForUser:(NSString *)user withPassword:(NSString *)pwd { NSString *a = [[NSString alloc] initWithFormat:@"%@ -> %@", user, pwd]; return a; } @end the method CalculateSecretForUser always says 'MainViewController' may not respond to '-calculateSecretForUser:withPassword:' what am I doing wrong here?

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• Add columns to SqlWebEventProvider

  - by Julien N

  In an asp.net application, we'd like to use the SqlWebEventProvider to log any Event that occurs during the application lifetime. The problem is that we think that the table aspnet_WebEvent_Event doesn't provide enough columns and should log more information (we need to keep the Logged user). I'm aware that this information could be stored in the "Details" column but it wouldn't then be really simple to filter the results and build reports. So I'm searching for a simple solution to add a column. I wish I could derive SqlWebEventProvider but the methods used to build the stocked procedure parameters are private (PrepareParams() and FillParams()). Any simple solution that doesn't imply to rewrite the entire Provider class ?

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• Codeigniter: Combining activeRecord with manual queries?

  - by Industrial

  Hi everybody, I've though a bit about the activerecord vs. manual queries in Codeigniter. ActiveRecord is awesome when it's all about standard queries and holds development time really low. However, when there's a need to add some complexity to the queries, the ActiveRecord gets quite complicated to work with. Sub queries or complex joins gives atleast me a lot of headache. Since the current "$this-db-query" -call immediately executes the set query, it can't be combined with normal activeRecord calls. So, what can I do to combine the two methods? Thanks!

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• asp.net mvc 2: SportsStore application: The current request for action is ambiguous

  - by dotnet-practitioner

  I am working on SportsStore example on chapter 4 from the following book and getting stuck... Pro Asp.net mvc framework I get the following error: The current request for action 'List' on controller type 'ProductsController' is ambiguous between the following action methods: System.Web.Mvc.ViewResult List() on type WebUI.Controllers.ProductsController System.Web.Mvc.ViewResult List(Int32) on type WebUI.Controllers.ProductsController .. My router code looks as follows: public static void RegisterRoutes(RouteCollection routes) { routes.MapRoute( null, // Route name "", // URL with parameters new { controller = "Products", action = "List", page=1 } ); routes.MapRoute( null, // Route name "Page{page}", // URL with parameters new { controller = "Products", action = "List" }, // Parameter defaults new { page = @"\d+" } ); } and controller code looks as follows: public ViewResult List() { return View(productsRepository.Products.ToList()); } public ViewResult List(int page) { return View(productsRepository.Products .Skip((page - 1) * PageSize) .Take(PageSize) .ToList()); } What am I missing? my url is as follows: http://localhost:1103/ or http://localhost:1103/Page1 or http://localhost:1103/Page2 thanks

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• Is yield break equivalent to returning Enumerable<T>.Empty from a method returning IEnumerable<T>

  - by Mike Two

  These two methods appear to behave the same to me public IEnumerable<string> GetNothing() { return Enumerable.Empty<string>(); } public IEnumerable<string> GetLessThanNothing() { yield break; } I've profiled each in test scenarios and I don't see a meaningful difference in speed, but the yield break version is slightly faster. Are there any reasons to use one over the other? Is one easier to read than the other? Is there a behavior difference that would matter to a caller?

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• Java: design problem with final-value and empty constructor

  - by HH

  $ javac InitInt.java InitInt.java:7: variable right might not have been initialized InitInt(){} ^ 1 error $ cat InitInt.java import java.util.*; import java.io.*; public class InitInt { private final int right; // Design Problem? // I feel the initialization problem is just due to bad style. InitInt(){} InitInt{ // Still the error, "may not be initialized" // How to initialise it? if(snippetBuilder.length()>(charwisePos+25)){ right=charwisePos+25; }else{ right=snippetBuilder.length()-1; } } public static void main(String[] args) { InitInt test = new InitInt(); System.out.println(test.getRight()); } public int getRight(){return right;} } Partial Solutions and Suggestions use "this" to access methods in the class, instead of creating empty constructor change final to non-final with final field value: initialize all final values in every constructor remove the empty constructor, keep your code simple and clean

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• UITableView's cellForRowAtIndexPath is not getting called after low memory warning

  - by Jinesh

  I am new to COCOA and Objective C. I am working on an application which have two controllers with one table view in each, clicking an item form this table will lead to another controller to be pushed to the stack. All was working fine till i started handling low memory warning in app delegate. What i am doing in app delegate's applicationDidReceiveMemoryWarning is, deleting all of my model and popping out all controllers to its root view using popToRootViewControllerAnimated. Now my problem starts, once low mem warning is received table's cellForRowAtIndexPath is not getting called. All other methods of UITableViewDataSource is properly called. What i get on screen is a blank white screen. I am testing my app in iPhone OS 3.0 and development is done in Xcode V 3.1.3. Hope you guys can help me to nail this. Thanks in advance, Jinesh.

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• How to prevent "Local transaction already has 1 non-XA Resource" exception?

  - by Zeratul

  Hi, I'm using 2 PU in stateless EJB and each of them is invoked on one method: @PersistenceContext(unitName="PU") private EntityManager em; @PersistenceContext(unitName="PU2") private EntityManager em2; @TransactionAttribute(TransactionAttributeType.REQUIRES_NEW ) public void getCandidates(final Integer eventId) throws ControllerException { ElectionEvent electionEvent = em.find(ElectionEvent.class, eventId); ... Person person = getPerson(candidate.getLogin()); ... } @TransactionAttribute(TransactionAttributeType.REQUIRES_NEW ) private Person getPerson(String login) throws ControllerException { Person person = em2.find(Person.class, login); return person; } Those methods are annotated with REQUIRES_NEW transcaction to avoid this exception. When I was calling these method from javaFX applet, all worked as expected. Now I'm trying to call them from JAX-RS webservice (I don't see any logical difference as in both cases ejb was looked up in initial context) and I keep getting this exception. When I set up XADatasource in glassfish 2.1 connection pools, I got nullpointer exception on em2. Any ideas what to try next? Regards

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• Method chaining and exceptions in C#

  - by devoured elysium

  If I have a method chain like the following: var abc = new ABC(); abc.method1() .method2() .methodThrowsException() .method3() ; assuming I've defined method1(), method2() and method3() as public ABC method1() { return this; } and methodThrowsException() as public ABC method3() { throw new ArgumentException(); } When running the code, is it possible to know which specific line of code has thrown the Exception, or will it just consider all the method chaining as just one line? I've done a simple test and it seems it considers them all as just one line but Method Chaining says Putting methods on separate lines also makes debugging easier as error messages and debugger control is usually on a line by line basis. Am I missing something, or does that just not apply to C#? Thanks

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• Implementing a Stack using Test-Driven Development

  - by devoured elysium

  I am doing my first steps with TDD. The problem is (as probably with everyone starting with TDD), I never know very well what kind of unit tests to do when I start working in my projects. Let's assume I want to write a Stack class with the following methods(I choose it as it's an easy example): Stack<T> - Push(element : T) - Pop() : T - Seek() : T - Count : int - IsEmpty : boolean How would you approch this? I never understood if the idea is to test a few corner cases for each method of the Stack class or start by doing a few "use cases" with the class, like adding 10 elements and removing them. What is the idea? To make code that uses the Stack as close as possible to what I'll use in my real code? Or just make simple "add one element" unit tests where I test if IsEmpty and Count were changed by adding that element? How am I supposed to start with this?

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• Out of Memory When Loading Java Entities

  - by Hugh Buchanan

  I have a terrible problem that hopefully has a very simple answer. I am running out of memory when I perform a basic If I have code like this: MyEntity myEntity; for (Object id: someIdList) { myEntity = find(id); // do something basic with myEntity } And the find() method is a standard EntityManager related method: public MyEntity find(Object id) { return em.find(mycorp.ejb.entity.MyEntity.class, id); } This code worked a couple of weeks ago, and works fine if there are fewer items in the database. The resulting error I am facing is: java.lang.OutOfMemoryError: GC overhead limit exceeded The exception is coming from oracle toplink calling some oracle jdbc methods. The loop exists because an EJBQL such as "select object(o) from MyEntity as o" will overload the application server when there are lots of records.

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• How to get the current project directory or the bin directory and move a few level up?

  - by melaos

  I have an ASP.Net MVC app, and i have some xsl files inside of the Content directory. I've try a few methods to get directory dynamically buy keep on coming short. So how do i get the directory to point to the Content/xsl folder? the closest that i came to was with this: this.GetType().Assembly.CodeBase which only returns the project DLL, but i can't figure out how to move up a few levels from there or what .net library to use to navigate around the path. there's no ../.. :( Basically i want to navigate to the Content/xsl folder which is at the same level of the Bin directory.

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• C++/CLI .ToString() returning error

  - by George Johnston

  I am a beginner to C++/CLI as I come from a C# background. I am currently writing a wrapper for some native C++ code. I have the following methods: void AddToBlockList(System::String^ address) { char* cAddress = (char*)(void*)Marshal::StringToHGlobalAnsi(address); _packetFilter->AddToBlockList(cAddress); } void AddToBlockList(IPAddress^ address) { char* cAddress = (char*)(void*)Marshal::StringToHGlobalAnsi(address.ToString()); _packetFilter->AddToBlockList(cAddress); } ...The first method works fine and converts my string into the character array. However, the second function with the IPAddress object as the signiture gives me the following error: error C2228: left of '.ToString' must have class/struct/union ...When I type ? address.ToString() ...in the command window, the IP Address prints. Not sure where I'm going wrong. Any ideas?

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• How do I properly handle a faulted WCF connection?

  - by mafutrct

  In my client program, there is a WCF connection that is opened at startup and supposedly stays connected til shutdown. However, there is a chance that the server closes due to unforeseeable circumstances (imagine someone pulling the cable). Since the client uses a lot of contract methods in a lot of places, I don't want to add a try/catch on every method call. I've got 2 ideas for handling this issue: Create a method that takes a delegate and executes the delegate inside a try/catch and returns an Exception in case of a known exception, or null else. The caller has to deal with nun-null results. Listen to the Faulted event of the underlying CommunicationObject. But I don't see how I could handle the event except for displaying some error message and shutting down. Are there some best practices for faulted WCF connection that exist for app lifetime?

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• Calculating Percentiles (Ruby).

  - by zxcvbnm

  My code is based on the methods described here and here. def fraction?(number) number - number.truncate end def percentile(param_array, percentage) another_array = param_array.to_a.sort r = percentage.to_f * (param_array.size.to_f - 1) + 1 if r <= 1 then return another_array[0] elsif r >= another_array.size then return another_array[another_array.size - 1] end ir = r.truncate another_array[ir] + fraction?((another_array[ir].to_f - another_array[ir - 1].to_f).abs) end Example usage: test_array = [95.1772, 95.1567, 95.1937, 95.1959, 95.1442, 95.061, 95.1591, 95.1195, 95.1065, 95.0925, 95.199, 95.1682] test_values = [0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0] test_values.each do |value| puts value.to_s + ": " + percentile(test_array, value).to_s end Output: 0.0: 95.061 0.1: 95.1205 0.2: 95.1325 0.3: 95.1689 0.4: 95.1692 0.5: 95.1615 0.6: 95.1773 0.7: 95.1862 0.8: 95.2102 0.9: 95.1981 1.0: 95.199 The problem here is that the 80th percentile is higher than the 90th and the 100th. However, as far as I can tell my implementation is as described, and it returns the right answer for the example given (0.9). Is there an error in my code I'm not seeing? Or is there a better way to do this?

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• C# Operator Overloading post-fix increment

  - by Victor

  I'm coding a date class and am having trouble with the post-fix increment (the prefix increment seems fine). Here is the sample code: public class date { int year, month, day; public date(int d, int m, int y) { day = d; month = m; year = y; } static public date operator ++(date d) { return d.Next(d); } } The method "Next(date d)" takes a date and returns tomorrows date (I left it out for brevity). I'm to young in C# to understand why the prefix is fine but postfix increment does nothing. But remember in C++ we would have to have two methods instead of just one - for prefix and postfix increments. Also no errors or warnings on compile.

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• getting the name of the calling method

  - by zeocrash

  Basically i've got a web service that i'm trying to put some kind of usage logging in. To do this i've created a class with a logging method. I instatiate the class on the service and then call the logging method in each of the web methods. I'm trying to find a way of getting the name of the method that has called the loggong method Public sub tstmethod log_object.log_method end sub in this case the returned name i'm looking for is "tstmethod" Everywhere i've seen has said to either use Dim stackframe As New Diagnostics.StackFrame Return stackframe.GetMethod.Name.ToString Or to use Dim stackframe As New Diagnostics.StackFrame Return stackframe.GetMethod.DeclaringType.FullName which i call inside the logging method getmethod.name.tostring returns the name of the logging method getmethod.declaringtype.fullname returns the name of the logging class no matter what i do i cannot find a way of getting the name of the method that called the logging method in this case "tstmethod"

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• IDL in ATL/COM: Can I publish a const of a complex type?

  - by Ptah- Opener of the Mouth

  I know how to publish a const of a simple type in IDL, for example: const long blah = 37 But I want to publish consts of complex types, with methods, or at least readable struct-like member fields. For example, perhaps a type called CarType, which has accessor fields like "get_Make", "get_Model", "get_Year", "get_BasePrice", et cetera. Then I would like to publish const instances, such as FORD_PINTO_1973. (Please don't read too much into the example, to tell me that this particular example would lend itself better to just regular classes without const instances or something like that). I have no idea how I would define, in IDL, the fact that FORD_PINTO_1973 has a Year field of 1973. Thanks in advance for any help.

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• asp.net - csharp - jquery - looking for a better and usage solution

  - by LostLord

  hi my dear friends i have a little problem about using jquery...(i reeally do not know jquery but i forced to use it) i am using vs 2008 - asp.net web app with c# also i am using telerik controls in my pages also i am using sqldatasources (Connecting to storedprocedures) in my pages my pages base on master and content pages and in content pages i have mutiviews ================================================================================= in one of the views(inside one of those multiviews)i had made two radcombo boxes for country and city requirement like cascading dropdowns as parent and child combo boxes. i used old way for doing that , i mean i used update panel and in the SelectedIndexChange Event of Parent RadComboBox(Country) i Wrote this code : protected void RadcomboboxCountry_SelectedIndexChanged(object o, RadComboBoxSelectedIndexChangedEventArgs e) { hfSelectedCo_ID.Value = RadcomboboxCountry.SelectedValue; RadcomboboxCity.Items.Clear(); RadcomboboxCity.Items.Add(new RadComboBoxItem(" ...", "5")); RadcomboboxCity.DataBind(); RadcomboboxCity.SelectedIndex = 0; } my child radcombo box can fill by upper code , let me tell you how : the child sqldatasource have a sp that has a parameter and i fill that parameter by this line - hfSelectedCo_ID.Value = RadcbCoNameInInsert.SelectedValue; RadcbCoNameInInsert.SelectedValue means country ID. after doing that SelectedIndexChange Event of Parent RadComboBox(Country) could not be fire therefore i forced to set the autopostback property to true. afetr doing that every thing was ok until some one told me can u control focus and keydown of your radcombo boxes (when u press enter key on the parent combobox[country] , so child combobox gets focus -- and when u press upperkey on child radcombobox [city], so parent combobox[country] gets focus) (For Users That Do Not Want To Use Mouse for Input Info And Choose items) i told him this is web app , not win form and we can not do that. i googled it and i found jquery the only way for doing that ... so i started using jquery . i wrote this code with jquery for both of them : <script src="../JQuery/jquery-1.4.1.js" language="javascript" type="text/javascript"></script> <script type="text/javascript"> $(function() { $('input[id$=RadcomboboxCountry_Input]').focus(); $('input[id$=RadcomboboxCountry_Input]').select(); $('input[id$=RadcomboboxCountry_Input]').bind('keyup', function(e) { var code = (e.keyCode ? e.keyCode : e.which); if (code == 13) { -----------> Enter Key $('input[id$=RadcomboboxCity_Input]').focus(); $('input[id$=RadcomboboxCity_Input]').select(); } }); $('input[id$=RadcomboboxCity_Input]').bind('keyup', function(e) { var code = (e.keyCode ? e.keyCode : e.which); if (code == 38) { -----------> Upper Key $('input[id$=RadcomboboxCountry_Input]').focus(); $('input[id$=RadcomboboxCountry_Input]').select(); } }); }); </script> this jquery code worked BBBBBBUUUUUUUTTTTTT autopostback=true of the Parent RadComboBox Became A Problem , Because when SelectedIndex Change Of ParentRadComboBox is fired after that Telerik Skins runs and after that i lost parent ComboBox Focus and we should use mouse but we don't want it.... for fix this problem i decided to set autopostback of perentCB to false and convert protected void RadcomboboxCountry_SelectedIndexChanged(object o, RadComboBoxSelectedIndexChangedEventArgs e) { hfSelectedCo_ID.Value = RadcomboboxCountry.SelectedValue; RadcomboboxCity.Items.Clear(); RadcomboboxCity.Items.Add(new RadComboBoxItem(" ...", "5")); RadcomboboxCity.DataBind(); RadcomboboxCity.SelectedIndex = 0; } to a public non static method without parameters and call it with jquey like this : (i used onclientchanged property of parentcombo box like onclientchanged = "MyMethodForParentCB_InJquery();" insread of selectedindexchange event) public void MyMethodForParentCB_InCodeBehind() { hfSelectedCo_ID.Value = RadcomboboxCountry.SelectedValue; RadcomboboxCity.Items.Clear(); RadcomboboxCity.Items.Add(new RadComboBoxItem(" ...", "5")); RadcomboboxCity.DataBind(); RadcomboboxCity.SelectedIndex = 0; } for doing that i read the blow manual and do that step by step : ======================================================================= http://www.ajaxprojects.com/ajax/tutorialdetails.php?itemid=732 ======================================================================= but this manual is about static methods and this is my new problem ... when i am using static method like : public static void MyMethodForParentCB_InCodeBehind() { hfSelectedCo_ID.Value = RadcomboboxCountry.SelectedValue; RadcomboboxCity.Items.Clear(); RadcomboboxCity.Items.Add(new RadComboBoxItem(" ...", "5")); RadcomboboxCity.DataBind(); RadcomboboxCity.SelectedIndex = 0; } so i recieved some errors and this method could not recognize my controls and hidden field... one of those errors like this : Error 2 An object reference is required for the non-static field, method, or property 'Darman.SuperAdmin.Users.hfSelectedCo_ID' C:\Javad\Copy of Darman 6\Darman\SuperAdmin\Users.aspx.cs 231 13 Darman any idea or is there any way to call non static methods with jquery (i know we can not do that but is there another way to solve my problem)???????????????

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• NSKeyedArchiver save method ( that i made) crashed the iphone simulator

  - by Kevin

  i saw this approach on a tutorial, and the message is working for their example but when i implement this it does not work. from what i can tell the iphone simulator crashes when i do a [ self saveSettingsData]. TheSettings is class object that i declare and initialize in the appdelagate with these methods. the error says terminating due to uncaught exception. i am new to the iphone sdk and objective, so i really can't figure out what is going on thanks to any one who can help, i am ready to literally pull my hair out. (NSString *) SettingsDataFilePath { NSString * settingsDataFilePath ; NSArray * paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) ; NSString * documentsDirectory = [paths objectAtIndex:0] ; settingsDataFilePath = [[documentsDirectory stringByAppendingPathComponent: @"SetggggtingsData.plist" ] retain] ; return settingsDataFilePath ; } (void) saveSettingsData { [NSKeyedArchiver archiveRootObject:[TheSettings copy] toFile:[self SettingsDataFilePath]] ;

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